Water-free etching methods

ABSTRACT

Exemplary cleaning or etching methods may include flowing a fluorine-containing precursor into a remote plasma region of a semiconductor processing chamber. Methods may include forming a plasma within the remote plasma region to generate plasma effluents of the fluorine-containing precursor. The methods may also include flowing the plasma effluents into a processing region of the semiconductor processing chamber. A substrate may be positioned within the processing region, and the substrate may include a region of exposed oxide and a region of exposed metal. Methods may also include providing a hydrogen-containing precursor to the processing region. The methods may further include removing at least a portion of the exposed oxide.

TECHNICAL FIELD

The present technology relates to semiconductor processes and equipment. More specifically, the present technology relates to cleaning or etching high-aspect-ratio structures.

BACKGROUND

Integrated circuits are made possible by processes which produce intricately patterned material layers on substrate surfaces. Producing patterned material on a substrate requires controlled methods for removal of exposed material. Chemical etching is used for a variety of purposes including transferring a pattern in photoresist into underlying layers, thinning layers, or thinning lateral dimensions of features already present on the surface. Often it is desirable to have an etch process that etches one material faster than another facilitating, for example, a pattern transfer process. Such an etch process is said to be selective to the first material. As a result of the diversity of materials, circuits, and processes, etch processes have been developed with a selectivity towards a variety of materials.

Etch processes may be termed wet or dry based on the materials used in the process. A wet HF etch preferentially removes silicon oxide over other dielectrics and materials. However, wet processes may have difficulty penetrating some constrained trenches and also may sometimes deform the remaining material. Dry etches produced in local plasmas formed within the substrate processing region can penetrate more constrained trenches and exhibit less deformation of delicate remaining structures. However, local plasmas may damage the substrate through the production of electric arcs as they discharge.

Thus, there is a need for improved systems and methods that can be used to produce high quality devices and structures. These and other needs are addressed by the present technology.

SUMMARY

Exemplary cleaning or etching methods may include flowing a fluorine-containing precursor into a remote plasma region of a semiconductor processing chamber. Methods may include forming a plasma within the remote plasma region to generate plasma effluents of the fluorine-containing precursor. The methods may also include flowing the plasma effluents into a processing region of the semiconductor processing chamber. A substrate may be positioned within the processing region, and the substrate may include a region of exposed oxide and a region of exposed metal. Methods may also include providing a hydrogen-containing precursor to the processing region. The methods may further include removing at least a portion of the exposed oxide.

In some embodiments, the methods may further include condensing the hydrogen-containing precursor on the region of exposed oxide. The hydrogen-containing precursor may include an alcohol. The alcohol may be selected from the group consisting of methanol, ethanol, propanol, butanol, and pentanol. The methods may include increasing a pressure within the processing chamber while removing at least a portion of the exposed oxide. The pressure may be increased by at least about 1 Torr. The fluorine-containing precursor may be or include nitrogen trifluoride. The methods may also include reducing a temperature within the processing chamber while removing at least a portion of the exposed oxide. The temperature may be reduced by at least about 5° C. The metal may be selected from the group consisting of tungsten, cobalt, and copper. The method may be performed without providing water to the processing chamber. The hydrogen-containing precursor may bypass the remote plasma region when provided to the processing region. The processing region may be maintained plasma free during the removing operations.

The present technology may also include removal methods. The methods may include flowing a fluorine-containing precursor into a processing region of a semiconductor processing chamber. The processing region may house a substrate comprising a high-aspect-ratio feature having an exposed region of oxide and an exposed region of metal-containing material. The methods may include, while flowing the fluorine-containing precursor into the processing region, providing a hydrogen-containing precursor to the processing region to produce an etchant. The methods may also include removing at least a portion of the exposed oxide with the etchant.

In some embodiments, the etchant may begin reacting with oxide without an incubation period. The hydrogen-containing precursor may include an alcohol. The fluorine-containing precursor may be or include hydrogen fluoride. The method may be performed at a processing temperature of below or about 10° C. The method may be performed at a processing pressure of below or about 50 Torr. The metal may be selected from the group consisting of cobalt, tungsten, and copper.

Such technology may provide numerous benefits over conventional systems and techniques. For example, the processes may allow high-aspect-ratio features to be etched without corroding exposed metal. Additionally, the processes may allow a material removal that requires no incubation period. These and other embodiments, along with many of their advantages and features, are described in more detail in conjunction with the below description and attached figures.

BRIEF DESCRIPTION OF THE DRAWINGS

A further understanding of the nature and advantages of the disclosed technology may be realized by reference to the remaining portions of the specification and the drawings.

FIG. 1 shows a top plan view of one embodiment of an exemplary processing system according to embodiments of the present technology.

FIG. 2 schematic cross-sectional view of an exemplary processing system

FIG. 3 shows exemplary operations in a method according to embodiments of the present technology.

FIGS. 4A-4B show cross-sectional views of substrates being processed according to embodiments of the present technology.

FIG. 5 shows exemplary operations in a method according to embodiments of the present technology.

Several of the figures are included as schematics. It is to be understood that the figures are for illustrative purposes, and are not to be considered of scale unless specifically stated to be of scale. Additionally, as schematics, the figures are provided to aid comprehension and may not include all aspects or information compared to realistic representations, and may include additional or exaggerated material for illustrative purposes.

In the appended figures, similar components and/or features may have the same reference label. Further, various components of the same type may be distinguished by following the reference label by a letter that distinguishes among the similar components. If only the first reference label is used in the specification, the description is applicable to any one of the similar components having the same first reference label irrespective of the letter.

DETAILED DESCRIPTION

Diluted acids may be used in many different semiconductor processes for cleaning substrates, and removing materials from those substrates. For example, diluted hydrofluoric acid can be an effective etchant for silicon oxide, and may be used to remove silicon oxide from silicon surfaces. After the etching or cleaning operation is complete, the acid may be dried from the wafer or substrate surface. Using dilute hydrofluoric acid (“DHF”) may be termed a “wet” etch, and the diluent is often water. Additional etching processes may be used that utilize precursors delivered to the substrate. For example, a plasma species may be delivered to a wafer along with water vapor to form an etchant mixture as well.

Although wet etchants using aqueous solutions or water-based processes may operate effectively for certain substrate structures, the water may pose issues when utilized on substrates including metal materials. For example, certain later fabrication processes, such as producing air gaps, may be performed after an amount of metallization has been formed on a substrate. If water is utilized in some fashion during the etching, an electrolyte may be produced, which when contacting the metal material, may cause galvanic corrosion to occur, and the metal may be corroded or displaced in various processes. Although some conventional processes have avoided this issue by utilizing alternative precursors, they may be unsuitable for fabrication processes in which multiple exposed materials are located, which may include silicon oxide, silicon nitride, as well as exposed metal.

The present technology overcomes these issues by performing a vapor phase etch process that does not utilize water as a precursor. The processes may or may not utilize plasma effluents as part of the etchant recipes in different embodiments. The technology may be capable of selectively etching silicon oxide relative to silicon nitride, high-quality oxides, as well as metal and metal-containing structures. An additional benefit is that by utilizing non-aqueous materials, the effect on substrate features may be minimized, such as by reducing the high surface tension associated with water. The term “dry” with respect to etching may be utilized to mean that liquid water may not be used in the operations, unlike with wet etches in which water may be used as a diluent or component, such as with DHF.

Although the remaining disclosure will routinely identify specific etching processes utilizing the disclosed technology, it will be readily understood that the systems and methods are equally applicable to deposition and cleaning processes as may occur in the described chambers, as well as other etching technology including back-end-of-line air gap formation and other etching that may be performed with exposed metal regions. Accordingly, the technology should not be considered to be so limited as for use with the exemplary etching processes or chambers alone. Moreover, although an exemplary chamber is described to provide foundation for the present technology, it is to be understood that the present technology can be applied to virtually any semiconductor processing chamber that may allow the operations described.

FIG. 1 shows a top plan view of one embodiment of a processing system 100 of deposition, etching, baking, and curing chambers according to embodiments. In the figure, a pair of front opening unified pods (FOUPs) 102 supply substrates of a variety of sizes that are received by robotic arms 104 and placed into a low pressure holding area 106 before being placed into one of the substrate processing chambers 108 a-f, positioned in tandem sections 109 a-c. A second robotic arm 110 may be used to transport the substrate wafers from the holding area 106 to the substrate processing chambers 108 a-f and back. Each substrate processing chamber 108 a-f, can be outfitted to perform a number of substrate processing operations including the dry etch processes described herein in addition to cyclical layer deposition (CLD), atomic layer deposition (ALD), chemical vapor deposition (CVD), physical vapor deposition (PVD), etch, pre-clean, degas, orientation, and other substrate processes.

The substrate processing chambers 108 a-f may include one or more system components for depositing, annealing, curing and/or etching a dielectric film on the substrate wafer. In one configuration, two pairs of the processing chambers, e.g., 108 c-d and 108 e-f, may be used to deposit dielectric material on the substrate, and the third pair of processing chambers, e.g., 108 a-b, may be used to etch the deposited dielectric. In another configuration, all three pairs of chambers, e.g., 108 a-f, may be configured to etch a dielectric film on the substrate. Any one or more of the processes described may be carried out in chamber(s) separated from the fabrication system shown in different embodiments. It will be appreciated that additional configurations of deposition, etching, annealing, and curing chambers for dielectric films are contemplated by system 100.

FIG. 2 shows a schematic cross-sectional view of an exemplary processing system 200 according to embodiments of the present technology. System 200 may include a processing chamber 205 and a remote plasma unit 210. The remote plasma unit 210 may be coupled with processing chamber 205 with one or more components. The remote plasma unit 210 may be coupled with one or more of a remote plasma unit adapter 215, an isolator 220, a pressure plate 225, and inlet adapter 230, a diffuser 235, or a mixing manifold 240. Mixing manifold 240 may be coupled with a top of processing chamber 205, and may be coupled with an inlet to processing chamber 205.

Remote plasma unit adapter 215 may be coupled with remote plasma unit 210 at a first end 211, and may be coupled with isolator 220 at a second end 212 opposite first end 211. Through remote plasma unit adapter 215 may be defined one or more channels. At first end 211 may be defined an opening or port to a channel 213. Channel 213 may be centrally defined within remote plasma unit adapter 215, and may be characterized by a first cross-sectional surface area in a direction normal to a central axis through remote plasma unit adapter 215, which may be in the direction of flow from the remote plasma unit 210. A diameter of channel 213 may be equal to or in common with an exit port from remote plasma unit 210. Channel 213 may be characterized by a length from the first end 211 to the second end 212. Channel 213 may extend through the entire length of remote plasma unit adapter 215, or a length less than the length from first end 211 to second end 212. For example, channel 213 may extend less than halfway of the length from the first end 211 to the second end 212, channel 213 may extend halfway of the length from the first end 211 to the second end 212, channel 213 may extend more than halfway of the length from the first end 211 to the second end 212, or channel 213 may extend about halfway of the length from the first end 211 to the second end 212 of remote plasma unit adapter 215.

Remote plasma unit adapter 215 may also define one or more trenches 214 defined beneath remote plasma unit adapter 215. Trenches 214 may be or include one or more annular recesses defined within remote plasma unit adapter 215 to allow seating of an o-ring or elastomeric element, which may allow coupling with an isolator 220.

Isolator 220 may be coupled with second end 212 of remote plasma unit adapter 215 in embodiments. Isolator 220 may be or include an annular member about an isolator channel 221. Isolator channel 221 may be axially aligned with a central axis in the direction of flow through remote plasma unit adapter 215. Isolator channel 221 may be characterized by a second cross-sectional area in a direction normal to a direction of flow through isolator 220. The second cross-sectional area may be equal to, greater than, or less than the first cross-sectional area of channel 213. In embodiments, isolator channel 221 may be characterized by a diameter greater than, equal to, or about the same as a diameter of channel 213 through remote plasma unit adapter 215.

Isolator 220 may be made of a similar or different material from remote plasma unit adapter 215, mixing manifold 240, or any other chamber component. In some embodiments, while remote plasma unit adapter 215 and mixing manifold 240 may be made of or include aluminum, including oxides of aluminum, treated aluminum on one or more surfaces, or some other material, isolator 220 may be or include a material that is less thermally conductive than other chamber components. In some embodiments, isolator 220 may be or include a ceramic, plastic, or other thermally insulating component configured to provide a thermal break between the remote plasma unit 210 and the chamber 205. During operation, remote plasma unit 210 may be cooled or operate at a lower temperature relative to chamber 205, while chamber 205 may be heated or operate at a higher temperature relative to remote plasma unit 210. Providing a ceramic or thermally insulating isolator 220 may prevent or limit thermal, electrical, or other interference between the components.

Coupled with isolator 220 may be a pressure plate 225. Pressure plate 225 may be or include aluminum or another material in embodiments, and pressure plate 225 may be made of or include a similar or different material than remote plasma unit adapter 215 or mixing manifold 240 in embodiments. Pressure plate 225 may define a central aperture 223 through pressure plate 225. Central aperture 223 may be characterized by a tapered shape through pressure plate 225 from a portion proximate isolator channel 221 to the opposite side of pressure plate 225. A portion of central aperture 223 proximate isolator channel 221 may be characterized by a cross-sectional area normal a direction of flow equal to or similar to a cross-sectional area of isolator channel 221. Central aperture 223 may be characterized by a percentage of taper of greater than or about 10% across a length of pressure plate 225, and may be characterized by a percentage of taper greater than or about 20%, greater than or about 30%, greater than or about 40%, greater than or about 50%, greater than or about 60%, greater than or about 70%, greater than or about 80%, greater than or about 90%, greater than or about 100%, greater than or about 150%, greater than or about 200%, greater than or about 300%, or greater in embodiments. Pressure plate 225 may also define one or more trenches 224 defined beneath isolator 220. Trenches 224 may be or include one or more annular recesses defined within pressure plate 225 to allow seating of an o-ring or elastomeric element, which may allow coupling with isolator 220.

An inlet adapter 230 may be coupled with pressure plate 225 at a first end 226, and coupled with diffuser 235 at a second end 227 opposite first end 226. Inlet adapter 230 may define a central channel 228 defined through inlet adapter 230. Central channel 228 may be characterized by a first portion 229 a, and a second portion 229 b. First portion 229 a may extend from first end 226 to a first length through inlet adapter 230, wherein central channel 228 may transition to second portion 229 b, which may extend to second end 227. First portion 229 a may be characterized by a first cross-sectional area or diameter, and second portion 229 b may be characterized by a second cross-sectional area or diameter less than the first. In embodiments the cross-sectional area or diameter of first portion 229 a may be twice as large as the cross-sectional area or diameter of second portion 229 b, and may be up to or greater than about three times as large, greater than or about 4 times as large, greater than or about 5 times as large, greater than or about 6 times as large, greater than or about 7 times as large, greater than or about 8 times as large, greater than or about 9 times as large, greater than or about 10 times as large, or greater in embodiments. Central channel 228 may be configured to provide plasma effluents of a precursor delivered from remote plasma unit 210 in embodiments, which may pass through channel 213 of remote plasma unit adapter 215, isolator channel 221 of isolator 220, and central aperture 223 of pressure plate 225.

Inlet adapter 230 may also define one or more second channels 231, which may extend from below first portion 229 a to or through second end 227. The second channels 231 may be characterized by a second cross-sectional surface area in a direction normal to the central axis through inlet adapter 230. The second cross-sectional surface area may be less than the cross-sectional surface area of first portion 229 a in embodiments, and may be greater than the cross-sectional surface area or a diameter of second portion 229 b. Second channels 231 may extend to an exit from inlet adapter 230 at second end 227, and may provide egress from adapter 230 for a precursor, such as a first bypass precursor, delivered alternately from the remote plasma unit 210. For example, second channel 231 may be fluidly accessible from a first port 232 defined along an exterior surface, such as a side, of inlet adapter 230, which may bypass remote plasma unit 210. First port 232 may be at or below first portion 229 a along a length of inlet adapter 230, and may be configured to provide fluid access to the second channel 231.

Second channel 231 may deliver the precursor through the inlet adapter 230 and out second end 227. Second channel 231 may be defined in a region of inlet adapter 230 between first portion 229 a and second end 227. In embodiments, second channel 231 may not be accessible from central channel 228. Second channel 231 may be configured to maintain a precursor fluidly isolated from plasma effluents delivered into central channel 228 from remote plasma unit 210. The first bypass precursor may not contact plasma effluents until exiting inlet adapter 230 through second end 227. Second channel 231 may include one or more channels defined in adapter 230. Second channel 231 may be centrally located within adapter 230, and may be associated with central channels 228. For example, second channel 231 may be concentrically aligned and defined about central channel 228 in embodiments. Second channel 231 may be an annular or cylindrical channel extending partially through a length or vertical cross-section of inlet adapter 230 in embodiments. In some embodiments, second channel 231 may also be a plurality of channels extending radially about central channel 228.

Inlet adapter 230 may also define one or more third channels 233, which may extend from below first portion 229 a to or through second end 227, and may extend from below a plane bisecting first port 232. The third channels 233 may be characterized by a third cross-sectional surface area in a direction normal to the central axis through inlet adapter 230. The third cross-sectional surface area may be less than the cross-sectional surface area of first portion 229 a in embodiments, and may be greater than the cross-sectional surface area or a diameter of second portion 229 b. The third cross-sectional surface area may also be equal to or similar to the cross-sectional surface area or a diameter of first portion 229 a as illustrated. For example, an outer diameter of third channel 233 may be equivalent to an outer diameter of first portion 229 a, or may be less than an outer diameter of first portion 229 a. Third channels 233 may extend to an exit from inlet adapter 230 at second end 227, and may provide egress from adapter 230 for a precursor, such as a second bypass precursor, delivered alternately from the remote plasma unit 210. For example, third channel 233 may be fluidly accessible from a second port 234 defined along an exterior surface, such as a side, of inlet adapter 230, which may bypass remote plasma unit 210. Second port 234 may be located on an opposite side or portion of inlet adapter 230 as first port 232. Second port 234 may be at or below first portion 229 a along a length of inlet adapter 230, and may be configured to provide fluid access to the third channel 233. Second port 234 may also be at or below first port 232 along a length of inlet adapter 230 in embodiments.

Third channel 233 may deliver the second bypass precursor through the inlet adapter 230 and out second end 227. Third channel 233 may be defined in a region of inlet adapter 230 between first portion 229 a and second end 227. In embodiments, third channel 233 may not be accessible from central channel 228. Third channel 233 may be configured to maintain a second bypass precursor fluidly isolated from plasma effluents delivered into central channel 228 from remote plasma unit 210, and from a first bypass precursor delivered into second channel 231 through first port 232. The second bypass precursor may not contact plasma effluents or a first bypass precursor until exiting inlet adapter 230 through second end 227. Third channel 233 may include one or more channels defined in adapter 230. Third channel 233 may be centrally located within adapter 230, and may be associated with central channels 228 and second channel 231. For example, third channel 233 may be concentrically aligned and defined about central channel 228 in embodiments, and may be concentrically aligned and defined about second channel 231. Third channel 233 may be a second annular or cylindrical channel extending partially through a length or vertical cross-section of inlet adapter 230 in embodiments. In some embodiments, third channel 233 may also be a plurality of channels extending radially about central channel 228.

Diffuser 235 may be positioned between inlet adapter 230 and mixing manifold 240 to maintain precursors delivered through inlet adapter 230 fluidly isolated until accessing mixing manifold 240. Diffuser 235 may be characterized by one or more channels, such as cylindrical or annular channels defined through diffuser 235. In embodiments, diffuser 235 may define a first channel 236 or central channel, a second channel 237, and a third channel 238. The channels may be characterized by similar dimensions or diameters as second portion 229 b of central channel 228, second channel 231, and third channel 233 of inlet adapter 230. For example, each channel may extend the inlet adapter channels to mixing manifold 240. Second channel 237 and third channel 238 may each be annular channels defined about first channel 236, and first channel 236, second channel 237, and third channel 238 may be concentrically aligned in embodiments and defined through diffuser 235.

Diffuser 235 may additionally define one or more trenches 239 about diffuser 235. For example, diffuser 235 may define a first trench 239 a, a second trench 239 b, and a third trench 239 c in embodiments, which may allow seating of o-rings or elastomeric members between inlet adapter 230 and diffuser 235. Each of trenches 239 may be an annular trench in embodiments that sits radially exterior to one or more of the channels defined through diffuser 235. First trench 239 a may be located radially outward of first channel 236, and may be located between first channel 236 and second channel 237. Second trench 239 b may be located radially outward of second channel 237, and may be located between second channel 237 and third channel 238. Third trench 239 c may be located radially outward of third channel 238. A diameter of each trench 239 may be greater than the channel to which it may be associated and to which it may be located radially exterior. The trenches may enable improved sealing between the inlet adapter 230 and the diffuser 235 to ensure precursors are maintained fluidly isolated between the components, and leaking between the channels does not occur.

Mixing manifold 240 may be coupled with diffuser 235 at a first end 241, and may be coupled with chamber 205 at a second end 242. Mixing manifold 240 may define an inlet 243 at first end 241. Inlet 243 may provide fluid access from diffuser 235, and inlet 243 may be characterized by a diameter equal to or about the same as a diameter of third channel 238 through diffuser 235. Inlet 243 may define a portion of a channel 244 through mixing manifold 240, and the channel 244 may be composed of one or more sections defining a profile of channel 244. Inlet 243 may be a first section in the direction of flow through channel 244 of mixing manifold 240. Inlet 243 may be characterized by a length that may be less than half a length in the direction of flow of mixing manifold 240. The length of inlet 243 may also be less than a third of the length of mixing manifold 240, and may be less than one quarter the length of mixing manifold 240 in embodiments. Inlet 243 may receive each precursor from diffuser 235, and may allow for mixing of the precursors, which may have been maintained fluidly isolated until delivery to mixing manifold 240.

Inlet 243 may extend to a second section of channel 244, which may be or include a tapered section 245. Tapered section 245 may extend from a first diameter equal to or similar to a diameter of inlet 243 to a second diameter less than the first diameter. In some embodiments, the second diameter may be about or less than half the first diameter. Tapered section 245 may be characterized by a percentage of taper of greater than or about 10%, greater than or about 20%, greater than or about 30%, greater than or about 40%, greater than or about 50%, greater than or about 60%, greater than or about 70%, greater than or about 80%, greater than or about 90%, greater than or about 100%, greater than or about 150%, greater than or about 200%, greater than or about 300%, or greater in embodiments.

Tapered section 245 may transition to a third region of channel 244, which may be a flared section 246. Flared section 246 may extend from tapered section 245 to an outlet of mixing manifold 240 at second end 242. Flared section 246 may extend from a first diameter equal to the second diameter of tapered section 245 to a second diameter greater than the first diameter. In some embodiments, the second diameter may be about or greater than double the first diameter. Flared section 246 may be characterized by a percentage of flare of greater than or about 10%, greater than or about 20%, greater than or about 30%, greater than or about 40%, greater than or about 50%, greater than or about 60%, greater than or about 70%, greater than or about 80%, greater than or about 90%, greater than or about 100%, greater than or about 150%, greater than or about 200%, greater than or about 300%, or greater in embodiments.

Flared section 246 may provide egress to precursors delivered through mixing manifold 240 through second end 242 via an outlet 247. The sections of channel 244 through mixing manifold 240 may be configured to provide adequate or thorough mixing of precursors delivered to the mixing manifold, before providing the mixed precursors into chamber 205. Unlike conventional technology, by performing the etchant or precursor mixing prior to delivery to a chamber, the present systems may provide an etchant having uniform properties prior to being distributed about a chamber and substrate. In this way, processes performed with the present technology may have more uniform results across a substrate surface.

Chamber 205 may include a number of components in a stacked arrangement. The chamber stack may include a gasbox 250, a blocker plate 260, a faceplate 270, an ion suppression element 280, and a lid spacer 290. The components may be utilized to distribute a precursor or set of precursors through the chamber to provide a uniform delivery of etchants or other precursors to a substrate for processing. In embodiments, these components may be stacked plates each at least partially defining an exterior of chamber 205.

Gasbox 250 may define a chamber inlet 252. A central channel 254 may be defined through gasbox 250 to deliver precursors into chamber 205. Inlet 252 may be aligned with outlet 247 of mixing manifold 240. Inlet 252 and/or central channel 254 may be characterized by a similar diameter in embodiments. Central channel 254 may extend through gasbox 250 and be configured to deliver one or more precursors into a volume 257 defined from above by gasbox 250. Gasbox 250 may include a first surface 253, such as a top surface, and a second surface 255 opposite the first surface 253, such as a bottom surface of gasbox 250. Top surface 253 may be a planar or substantially planar surface in embodiments. Coupled with top surface 253 may be a heater 248.

Heater 248 may be configured to heat chamber 205 in embodiments, and may conductively heat each lid stack component. Heater 248 may be any kind of heater including a fluid heater, electrical heater, microwave heater, or other device configured to deliver heat conductively to chamber 205. In some embodiments, heater 248 may be or include an electrical heater formed in an annular pattern about first surface 253 of gasbox 250. The heater may be defined across the gasbox 250, and around mixing manifold 240. The heater may be a plate heater or resistive element heater that may be configured to provide up to, about, or greater than about 2,000 W of heat, and may be configured to provide greater than or about 2,500 W, greater than or about 3,000 W, greater than or about 3,500 W, greater than or about 4,000 W, greater than or about 4,500 W, greater than or about 5,000 W, or more.

Heater 248 may be configured to produce a variable chamber component temperature up to, about, or greater than about 50° C., and may be configured to produce a chamber component temperature greater than or about 75° C., greater than or about 100° C., greater than or about 150° C., greater than or about 200° C., greater than or about 250° C., greater than or about 300° C., or higher in embodiments. Heater 248 may be configured to raise individual components, such as the ion suppression element 280, to any of these temperatures to facilitate processing operations, such as an anneal. In some processing operations, a substrate may be raised toward the ion suppression element 280 for an annealing operation, and heater 248 may be adjusted to conductively raise the temperature of the heater to any particular temperature noted above, or within any range of temperatures within or between any of the stated temperatures.

Second surface 255 of gasbox 250 may be coupled with blocker plate 260. Blocker plate 260 may be characterized by a diameter equal to or similar to a diameter of gasbox 250. Blocker plate 260 may define a plurality of apertures 263 through blocker plate 260, only a sample of which are illustrated, which may allow distribution of precursors, such as etchants, from volume 257, and may begin distributing precursors through chamber 205 for a uniform delivery to a substrate. Although only a few apertures 263 are illustrated, it is to be understood that blocker plate 260 may have any number of apertures 263 defined through the structure. Blocker plate 260 may be characterized by a raised annular section 265 at an external diameter of the blocker plate 260, and a lowered annular section 266 at an external diameter of the blocker plate 260. Raised annular section 265 may provide structural rigidity for the blocker plate 260, and may define sides or an external diameter of volume 257 in embodiments. Blocker plate 260 may also define a bottom of volume 257 from below. Volume 257 may allow distribution of precursors from central channel 254 of gasbox 250 before passing through apertures 263 of blocker plate 260. Lowered annular section 266 may also provide structural rigidity for the blocker plate 260, and may define sides or an external diameter of a second volume 258 in embodiments. Blocker plate 260 may also define a top of volume 258 from above, while a bottom of volume 258 may be defined by faceplate 270 from below.

Faceplate 270 may include a first surface 272 and a second surface 274 opposite the first surface 272. Faceplate 270 may be coupled with blocker plate 260 at first surface 272, which may engage lowered annular section 266 of blocker plate 260. Faceplate 270 may define a ledge 273 at an interior of second surface 274, extending to third volume 275 at least partially defined within or by faceplate 270. For example, faceplate 270 may define sides or an external diameter of third volume 275 as well as a top of volume 275 from above, while ion suppression element 280 may define third volume 275 from below. Faceplate 270 may define a plurality of channels through the faceplate, although not illustrated in FIG. 2.

Ion suppression element 280 may be positioned proximate the second surface 274 of faceplate 270, and may be coupled with faceplate 270 at second surface 274. Ion suppression element 280 may be configured to reduce ionic migration into a processing region of chamber 205 housing a substrate. Ion suppression element 280 may define a plurality of apertures through the structure, although not illustrated in FIG. 2. In embodiments, gasbox 250, blocker plate 260, faceplate 270, and ion suppression element 280 may be coupled together, and in embodiments may be directly coupled together. By directly coupling the components, heat generated by heater 248 may be conducted through the components to maintain a particular chamber temperature that may be maintained with less variation between components. Ion suppression element 280 may also contact lid spacer 290, which together may at least partially define a plasma processing region in which a substrate is maintained during processing.

The chamber discussed previously may be used in performing exemplary methods including etching methods. Turning to FIG. 3 is shown exemplary operations in a method 300 according to embodiments of the present technology. Prior to the first operation of the method a substrate may be processed in one or more ways before being placed within a processing region of a chamber in which method 300 may be performed. For example, trenches, holes, or other features may be formed in a substrate, which may include a silicon substrate. The processes may include forming various structures, which may include metallization as well as forming lining and other structural features to separate nodes on a substrate. Some or all of these operations may be performed in chambers or system tools as previously described, or may be performed in different chambers on the same system tool, which may include the chamber in which the operations of method 300 are performed.

The method 300 may include flowing a fluorine-containing precursor into a remote plasma region of a semiconductor processing chamber at operation 305. An exemplary chamber may be chamber 205 previously described, which may include one or both of the RPS unit 210 or a first plasma region within the chamber. Either or both of these regions may be the remote plasma region used in operation 305. A plasma may be generated within the remote plasma region at operation 310, which may generate plasma effluents of the fluorine-containing precursor. The plasma effluents may be flowed to a processing region of the chamber at operation 315. The plasma effluents may interact with the substrate in the processing region, which may include various structural features and formations including multiple materials, or any other substrate or combination of elements as would be understood in semiconductor fabrication.

The substrate may include a region of exposed oxide, which may be from one or more sources. For example, the oxide may be an oxide hardmask that remains after trenches or other features have been formed, and may be a thermal oxide. The oxide may also be or include a layer of oxide that has been formed between nodes including a CVD or other deposited dielectric material. At operation 320, a hydrogen-containing precursor may be provided to the processing region along with the plasma effluents. The plasma effluents and hydrogen-containing precursor may interact with the exposed oxide to remove at least a portion of the exposed oxide at operation 325.

Precursors used in the method may include a fluorine-containing precursor or a halogen-containing precursor. An exemplary fluorine-containing precursor may be nitrogen trifluoride (NF₃), which may be flowed into the remote plasma region, which may be separate from, but fluidly coupled with, the processing region. Other sources of fluorine may be used in conjunction with or as replacements for the nitrogen trifluoride. In general, a fluorine-containing precursor may be flowed into the remote plasma region and the fluorine-containing precursor may include at least one precursor selected from the group of atomic fluorine, diatomic fluorine, nitrogen trifluoride, carbon tetrafluoride, hydrogen fluoride, xenon difluoride, and various other fluorine-containing precursors used or useful in semiconductor processing. The precursors may also include any number of carrier gases, which may include nitrogen, helium, argon, or other noble, inert, or useful precursors.

The hydrogen-containing precursor may include hydrogen, a hydrocarbon, an alcohol, hydrogen peroxide, or other materials that may include hydrogen as would be understood by the skilled artisan. Additional precursors such as carrier gases or inert materials may be included with the secondary precursors as well. One or more of the precursors may bypass the remote plasma region and be flowed into additional regions of the processing chamber. These precursors may be mixed with the plasma effluents in the processing region or some other region of the chamber. For example, while the fluorine-containing precursor is flowed through the remote plasma region to produce fluorine-containing plasma effluents, the hydrogen-containing precursor may bypass the remote plasma region. The hydrogen-containing precursor may bypass the remote plasma region by a bypass at a top of the chamber, or may be flowed into a separate region of the chamber, such as through a port providing access to the components previously described. The hydrogen-containing precursor may then flow into the processing region, where it may then mix or interact with fluorine-containing plasma effluents. In embodiments, the plasma processing region may be maintained plasma free during the removal operations. By plasma free is meant that plasma may not be actively formed within the processing region during the operations, although plasma effluents produced remotely as described earlier, may be used during the operations.

In some embodiments, the hydrogen-containing precursor may not be water, and in some embodiments, water may not be delivered as a precursor into the processing region. Substrates on which the method 300 may be performed may include substrates having exposed regions of a metal or a metal-containing material as well as exposed regions of oxide. Additional materials that may be exposed include silicon, nitrides, oxides, including metal nitrides or metal oxides. The etching process may include condensing the hydrogen-containing precursor on one or more regions of the substrate, or across a surface of the substrate. The fluorine-containing plasma effluents may then interact with the liquid to produce an etchant. Etching processes that utilize water as one of the precursors may also expose the metal or metal-containing materials to water, which may corrode the material. For example, galvanic corrosion may occur, which may etch or displace portions of the metal, deforming the structures. Accordingly, when water is not included as a precursor, this type of corrosion or deformation may be limited or avoided.

The reaction process with an alcohol and a halogen-containing precursor, which may be a fluorine-containing precursor or other halogen, may dissociate the fluorine-containing materials to form an etchant. The silicon oxide may receive a proton, such as hydrogen, which may then be etched by the etchant to produce volatile components and other reaction byproducts.

The reaction byproducts may include water in some embodiments. Although water may be produced, the amount of water may be much less than in processes utilizing water as a precursor, and thus the water produced as a reaction byproduct may be acceptable. Additionally, the alcohol may also help carry off and remove the water byproduct from interacting with metal or metal-containing materials on the substrate.

Alcohols utilized in the present technology may include any material including a bonded —OH, and may include monohydric alcohols, polyhydric alcohols, aliphatic alcohols, or alicyclic alcohols. Exemplary alcohols may include methanol, ethanol, propanol, butanol, pentanol, diols, triols, or other alcohol containing materials. For example, ethanol may be utilized in some embodiments, and butanol may be used in some embodiments. Longer chain alcohols may be characterized by a lower vapor pressure, which may facilitate condensation, enabling certain etch processes or increasing etch rates. A longer chain alcohol may also facilitate lower processing chamber pressures, which may reduce nitride etching, increasing selectivity of the oxide etch compared to exposed regions of nitride.

Another benefit of the present technology is that the process may not be characterized by an incubation prior to etching. Some processes utilizing plasma precursors or water may have a period of incubation prior to initiating the etching, which may then occur more rapidly. These processes may be more difficult to tune because of the waiting period followed by a rapid etching. Additionally, some conventional techniques may perform processes that produce solid byproducts that are removed prior to continued etching, which may be performed in cycles of etching and then removal of byproducts. This process may be more time consuming for high aspect ratio features, which may require many cycles to complete the etch process. The present technology may not suffer from these deficiencies, as solid byproducts may not be formed, and the etching may initiate upon contact with the oxide material. For example, the hydrogen-containing precursor, which may be an alcohol, may condense on the surface of the substrate, and may interact with the fluorine-containing precursor, which may dissociate and begin etching without incubation.

Additional aspects of the present technology may be further understood with reference to FIGS. 4A-4B. FIG. 4 shows cross-sectional views of substrates being processed according to embodiments of the present technology. Beginning with FIG. 4A is shown a cross-sectional view of a substrate on which the present technology may be utilized. For example, a silicon substrate 405 may have one or more features formed or defined within or on a surface. The surface may have one or more materials formed including metal or metal-containing materials. For example, substrate 405 may have overlying materials including liners, silicides, and other materials used in transistor formation. As illustrated, substrate 405 may have a silicide material 410 formed, which may be a metal-containing material, such as cobalt silicide, for example, or any other material that may facilitate metal formation on a silicon substrate.

The substrate may also include a liner material 415, which may be a nitride, such as a metal-containing nitride, such as titanium nitride, for example. The structure may define one or more trenches 425. Within the trench 425, and or along a surface of the substrate, may be a metal material 420, such as tungsten, cobalt, or copper, for example. Additionally within the trench, may be a nitride material 430 overlying the metal material 420. On either side of metal material 420 and nitride material 430 may be an oxide material 435. In embodiments encompassed by the present technology, oxide material 435 may be removed in order to produce air gaps about metal material 420. The trench 425 may be a high-aspect-ratio trench as previously discussed, and may have an aspect ratio greater than 10, greater than 50, greater than 100, or within any of these numbers or others as deeper, narrower trenches may be formed. FIG. 4 includes merely exemplary structures and materials, and any of the materials may be different in other processes according to the present technology. For example, the metal or metal-containing materials may include tungsten, cobalt, copper, titanium, or other metals, and may include oxides, nitrides, silicides, or other structures including any of these materials. For example, additional compounds may include titanium nitride, tantalum nitride, cobalt silicide, or any other materials and metal-containing materials used in fabrication. The present technology may be equally applicable to any number of structures in which an oxide material is to be removed, and where exposed regions of metal may be included as well.

Operations of a process, such as selected operations of process 300 described previously, may be performed to remove the exposed oxide material from the surface of the silicon substrate 405. For example, a hydrogen-containing precursor and plasma effluents of a fluorine-containing precursor may be delivered to the processing region to at least partially remove the oxide material 435. As illustrated in FIG. 4B, the etching operations may remove the oxide material from about metal material 420 and nitride material 430, to provide air gaps. Because the trench 425 along with any other features may have high aspect ratios, etching processes may utilize the previously described materials in order to facilitate consistent etching, without requiring removal of byproducts as operations of the process. In this way, a continuous etching process may be performed as precursors are continued to be delivered to the processing region. Additionally, by utilizing an alcohol as one of the precursors, the present technology may not remove or corrode the exposed metal and metal-containing materials about the substrate, which may be contacted by the etchant materials.

Process conditions may also impact the operations performed in method 300 as well as other removal methods according to the present technology. Each of the operations of method 400 may be performed during a constant temperature in embodiments, while in some embodiments the temperature may be adjusted during different operations. For example, the substrate, pedestal, or chamber temperature during the method 300 may be maintained below or about 50° C. in embodiments. The substrate temperature may also be maintained below or about 45° C., below or about 40° C., below or about 35° C., below or about 30° C., below or about 25° C., below or about 20° C., below or about 15° C., below or about 10° C., below or about 5° C., below or about 0° C., below or about −5° C., or lower. By utilizing hydrogen-containing precursors that may not include water in embodiments, lower temperatures may be utilized with reduced concern for freezing on the substrate. The temperature may also be maintained at any temperature within these ranges, within smaller ranges encompassed by these ranges, or between any of these ranges.

In some embodiments the removal operation 325 may be performed at a first temperature, and a second temperature, or may be performed while temperature is modulated from a first temperature to a second temperature. Either or both of the temperatures may be within any of the ranges previously described. The second temperature may be lower than the first temperature in embodiments. For example, the temperature of the substrate may be lowered from the first temperature to the second temperature. By lowering the temperature of the substrate, the saturation at the wafer level may also be increased without adding substantially more precursor to the processing chamber. The opportunity for precursor droplets to form on the chamber components or on the substrate may then be reduced, which may aid in reducing or preventing pattern deformation or collapse.

For example, the first temperature may be less than or about 20° C., and the second temperature may be less than or about 10° C. in embodiments. The temperatures may be within any of the previously described ranges. In some embodiments, the first temperature may be between about 0° C. and about 20° C., between about 1° C. and about 15° C., between about 1° C. and about 10° C., or may be about 4° C., about 5° C., about 6° C., or about 7° C. in embodiments. Additionally, in embodiments the second temperature may be between about −5° C. and about 10° C., between about −5° C. and about 5° C., between about −1° C. and about 5° C., or may be about 1° C., about 2° C., about 3° C., or about 4° C. in embodiments. The temperature reduction between the first temperature and the second temperature may be at least about 2° C. in embodiments, and may be at least or about 3° C., at least or about 4° C., at least or about 5° C., at least or about 6° C., at least or about 7° C., at least or about 8° C., at least or about 9° C., at least or about 10° C., at least or about 11° C., at least or about 12° C., or more. Additionally, the temperature decrease may be less than or about 15° C., or any smaller range between any of these ranges or within any of these ranges.

The pressure within the chamber may also affect the operations performed, and in embodiments the chamber pressure may be maintained below about 50 Torr, below or about 40 Torr, below or about 30 Torr, below or about 25 Torr, below or about 20 Torr, below or about 15 Torr, below or about 10 Torr, below or about 5 Torr, below or about 1 Torr, or less. The pressure may also be maintained at any pressure within these ranges, within smaller ranges encompassed by these ranges, or between any of these ranges. By performing the operations at pressures below about 30 Torr, the selectivity of the process with respect to a nitrogen-containing material may be increased.

In some embodiments the removal operation 325 may be performed at a first pressure and a second pressure, and may be performed while modulating pressure within the chamber. Either or both of the pressures may be within any of the ranges previously described. The second pressure may be higher than the first pressure in embodiments. For example, the pressure within the processing chamber may be increased from the first pressure to the second pressure. By increasing the pressure within the chamber, the condensation at the wafer level may also be increased without adding substantially more precursor to the processing chamber. The opportunity for droplets to form on the chamber components or on the substrate may then be reduced, which again may aid in reducing or preventing pattern deformation or collapse.

For example, the first pressure may be less than or about 20 Torr, and the second pressure may be greater than or about 30 Torr in embodiments. In embodiments, the first pressure may be between about 1 Torr and about 25 Torr, between about 1 Torr and about 20 Torr, between about 1 Torr and about 15 Torr, or may be within any of the previously stated ranges. In some embodiments, the second pressure may be between about 0 Torr and about 30 Torr, between about 5 Torr and about 25 Torr, between about 10 Torr and about 20 Torr, or may be within any of the previously stated ranges. The pressure increase between the first pressure and the second pressure may be at least about 1 Torr in embodiments, and may be at least or about 2 Torr, at least or about 3 Torr, at least or about 4 Torr, at least or about 5 Torr, at least or about 6 Torr, at least or about 7 Torr, at least or about 8 Torr, or more in embodiments. The pressure increase may be less than or about 10 Torr in embodiments, or may be a smaller range within any of these ranges or between any of these ranges.

The flow rates of one or more of the precursors may also be adjusted with any of the other processing conditions. For example, a flow rate of the fluorine-containing precursor may be reduced, maintained, or increased during the removal operations. During any of the operations of method 300, the flow rate of the fluorine-containing precursor may be between about 2 sccm and about 100 sccm. Additionally, the flow rate of the fluorine-containing precursor may be at least or about 5 sccm, at least or about 10 sccm, at least or about 15 sccm, at least or about 20 sccm, at least or about 25 sccm, at least or about 30 sccm, at least or about 40 sccm, at least or about 50 sccm, at least or about 60 sccm, at least or about 80 sccm, at least or about 100 sccm, at least or about 120 sccm, at least or about 150 sccm, or more. The flow rate may also be between any of these stated flow rates, or within smaller ranges encompassed by any of these numbers.

The hydrogen-containing precursor may be flowed at any of these flow rates depending on the precursor used, which may be any number of hydrogen-containing precursors. For example, if an alcohol is utilized, the alcohol may be introduced at a rate of at least or about 0.5 g/min. The alcohol may also be introduced at a rate of at least or about 1 g/min, at least or about 2 g/min, at least or about 3 g/min, at least or about 4 g/min, at least or about 5 g/min, at least or about 6 g/min, at least or about 7 g/min, at least or about 8 g/min, at least or about 9 g/min, or more, although the alcohol may be introduced below about 10 g/min to reduce condensation on components and the substrate. The alcohol may also be introduced at a flow rate between any of these stated flow rates, or within smaller ranges encompassed by any of these numbers.

At the completion of method 300, a concentration of fluorine in the substrate may be below or about 8% in embodiments, and may be below or about 7%, below or about 6%, below or about 5%, below or about 4%, below or about 3%, below or about 2%, below or about 1%, or less. Similarly, a concentration of oxygen in the substrate may be below or about 15% in embodiments, and may be below or about 12%, below or about 10%, below or about 9%, below or about 8%, below or about 7%, below or about 6%, below or about 5%, below or about 4%, below or about 3%, below or about 2%, below or about 1%, or less.

Turning to FIG. 5 is shown exemplary operations in a method 500 according to embodiments of the present technology. Method 500 may include some or all of the operations, conditions, precursors, parameters, or results of method 300 described previously, or of any of the conditions discussed with relation to FIG. 4. Method 500 may be an additional method for performing removals including those described with respect to FIG. 4. In some embodiments, method 500 may differ from method 300 in that method 500 may not utilize plasma effluents. For example, method 500 may flow a fluorine-containing or other halogen-containing precursor to the substrate without exposing the precursor to a plasma. The halogen-containing precursor may be flowed into a processing region of the chamber at operation 510. A substrate may be housed within the processing region, and the substrate may be characterized by a high-aspect-ratio feature having a region of exposed oxide and a region of exposed metal or metal-containing material.

A hydrogen-containing precursor may be flowed into the processing region at operation 615. The hydrogen-containing precursor and the fluorine-containing precursor may be co-flowed into the processing region, and may be flowed through different or similar portions of the processing chamber. For example, both precursors may be flowed through an entrance to the chamber, or the fluorine-containing precursor may be flowed through a first access to the chamber, and the hydrogen-containing precursor may be flowed through a second access to the chamber. At operation 520 at least a portion of the exposed oxide may be removed while maintaining the metal or metal-containing materials on the substrate, or by performing a minimal etch of those materials. The precursors may be any of the previously noted precursors, and in embodiments, the fluorine-containing precursor may be or include hydrogen fluoride, and the hydrogen-containing precursor may be or include an alcohol. Method 500 may be performed without utilizing water as a precursor, and may not include providing water to the processing chamber, although water may be a reaction byproduct in some embodiments.

For example, based on the chamber conditions as previously noted, an alcohol may be delivered to the processing chamber, and may condense on exposed surfaces of the substrate. These surfaces may include an oxygen-containing material to be removed, such as an oxide, and may include one or more materials to be maintained or minimally reduced, such as a metal or metal-containing materials, a silicon or silicon-containing material, a nitride, or other exposed materials. When the hydrogen fluoride interacts with the condensed alcohol, the hydrogen fluoride may be dissociated to produce an etchant that may modify and etch silicon oxide, for example.

The present technology may selectively etch silicon oxide compared to other materials, and may selectively etch some types of silicon oxide relative to other types of silicon oxide. For example, the present technology may etch deposited silicon oxides relative to thermal oxide at a rate of at least about 10:1, and may etch deposited oxides relative to thermal oxide at a rate of at least about 15:1, at least about 20:1, at least about 50:1, at least about 100:1, or more. Deposited oxides may include spin on dielectrics, or deposition techniques including CVD, PECVD, and other deposition techniques. The present technology may also etch silicon oxide relative to silicon nitride at a rate of at least about 20:1, at least about 25:1, at least about 30:1, at least about 50:1, at least about 100:1, at least about 150:1, or more. The present technology may also etch silicon oxide relative to titanium nitride at a rate of at least about 50:1, at least about 75:1, at least about 100:1, at least about 150:1, at least about 200:1, at least about 300:1, or more. The present technology may also etch silicon oxide relative to any of the previously noted metals and metal containing materials at a rate of at least about 20:1, at least about 25:1, at least about 30:1, at least about 50:1, at least about 100:1, at least about 150:1, at least about 200:1, at least about 250:1, at least about 300:1, at least about 350:1, at least about 400:1, at least about 450:1, at least about 500:1, or more.

The previously discussed methods may allow the removal of oxide material from a substrate while limiting the fluorine incorporation, while maintaining critical dimensions of the substrate features, which may be high-aspect-ratio features, and while maintaining other materials including metal and metal-containing materials, and other silicon-containing materials. The operations performed may include one or more of increasing the fluorine-containing precursor flow rate during the removal, or continuing the removal for a period of time as discussed. Additional chamber operations may also be adjusted as discussed throughout the present disclosure. By utilizing the present methods and operations, high-aspect-ratio features may be cleaned or etched while not causing pattern collapse, unlike wet etching, and while not increasing or while limiting impurity inclusion such as fluorine, unlike some conventional dry etching.

In the preceding description, for the purposes of explanation, numerous details have been set forth in order to provide an understanding of various embodiments of the present technology. It will be apparent to one skilled in the art, however, that certain embodiments may be practiced without some of these details, or with additional details.

Having disclosed several embodiments, it will be recognized by those of skill in the art that various modifications, alternative constructions, and equivalents may be used without departing from the spirit of the embodiments. Additionally, a number of well-known processes and elements have not been described in order to avoid unnecessarily obscuring the present technology. Accordingly, the above description should not be taken as limiting the scope of the technology. Additionally, methods or processes may be described as sequential or in steps, but it is to be understood that the operations may be performed concurrently, or in different orders than listed.

Where a range of values is provided, it is understood that each intervening value, to the smallest fraction of the unit of the lower limit, unless the context clearly dictates otherwise, between the upper and lower limits of that range is also specifically disclosed. Any narrower range between any stated values or unstated intervening values in a stated range and any other stated or intervening value in that stated range is encompassed. The upper and lower limits of those smaller ranges may independently be included or excluded in the range, and each range where either, neither, or both limits are included in the smaller ranges is also encompassed within the technology, subject to any specifically excluded limit in the stated range. Where the stated range includes one or both of the limits, ranges excluding either or both of those included limits are also included.

As used herein and in the appended claims, the singular forms “a”, “an”, and “the” include plural references unless the context clearly dictates otherwise. Thus, for example, reference to “a precursor” includes a plurality of such precursors, and reference to “the layer” includes reference to one or more layers and equivalents thereof known to those skilled in the art, and so forth.

Also, the words “comprise(s)”, “comprising”, “contain(s)”, “containing”, “include(s)”, and “including”, when used in this specification and in the following claims, are intended to specify the presence of stated features, integers, components, or operations, but they do not preclude the presence or addition of one or more other features, integers, components, operations, acts, or groups. 

1. An etching method comprising: flowing a fluorine-containing precursor into a remote plasma region of a semiconductor processing chamber; forming a plasma within the remote plasma region to generate plasma effluents of the fluorine-containing precursor; flowing the plasma effluents into a processing region of the semiconductor processing chamber, wherein the processing region houses a substrate comprising a region of exposed oxide and an exposed region of metal; providing a hydrogen-containing precursor to the processing region; condensing the hydrogen-containing precursor on the region of exposed oxide; and removing at least a portion of the exposed oxide.
 2. (canceled)
 3. The etching method of claim 1, wherein the hydrogen-containing precursor comprises an alcohol.
 4. The etching method of claim 3, wherein the alcohol is selected from the group consisting of methanol, ethanol, propanol, butanol, and pentanol.
 5. The etching method of claim 1, further comprising increasing a pressure within the processing chamber while removing at least a portion of the exposed oxide.
 6. The etching method of claim 5, wherein the pressure is increased by at least about 1 Torr.
 7. The removal method of claim 1, wherein the fluorine-containing precursor comprises nitrogen trifluoride.
 8. The etching method of claim 1, further comprising reducing a temperature within the processing chamber while removing at least a portion of the exposed oxide.
 9. The etching method of claim 8, wherein the temperature is reduced by at least about 5° C.
 10. The etching method of claim 1, wherein the metal is selected from the group consisting of tungsten, cobalt, copper, titanium nitride, tantalum nitride, and cobalt silicide.
 11. The etching method of claim 1, wherein the method is performed without providing water to the processing chamber.
 12. The etching method of claim 1, wherein the hydrogen-containing precursor bypasses the remote plasma region when provided to the processing region.
 13. The etching method of claim 1, wherein the processing region is maintained plasma free during the removing operations.
 14. A removal method comprising: flowing a fluorine-containing precursor into a processing region of a semiconductor processing chamber, wherein the processing region houses a substrate comprising a high-aspect-ratio feature having an exposed region of oxide and an exposed region of metal-containing material; while flowing the fluorine-containing precursor into the processing region, providing a hydrogen-containing precursor to the processing region to produce an etchant; and removing at least a portion of the exposed oxide with the etchant, wherein the processing region is maintained plasma free during the removing operations.
 15. The removal method of claim 14, wherein the etchant begins reacting with oxide without an incubation period.
 16. The removal method of claim 14, wherein the hydrogen-containing precursor comprises an alcohol.
 17. The removal method of claim 14, wherein the fluorine-containing precursor comprises hydrogen fluoride.
 18. The removal method of claim 14, wherein the method is performed at a processing temperature of below or about 10° C.
 19. The removal method of claim 14, wherein the method is performed at a processing pressure of below or about 50 Torr.
 20. The removal method of claim 14, wherein the metal is selected from the group consisting of cobalt, tungsten, and copper. 